Equation for fitting desorption isotherms of durum wheat pasta

Summary This work was undertaken to obtain water vapour desorption data for durum wheat pasta (spaghetti) between 40° and 90°C by an equilibrium method using sulphuric acid solutions. Sorption isotherms were also measured for semolina of the same composition. From these data the net heat of desorption, calculated by the Clausius-Clapeyron relationship, and BET monolayer values Xm were determined. In the range of water activity (aw) investigated, i.e. 0.10 < aw < 0.90, the results were correlated to an Oswin type empirical relation X=f(aw, T) with a mean precision of 7%. This equation should be of use in modelling pasta drying.